The disclosure herein relates to methods and systems for tracking pacing effectiveness by monitoring the electrical vectors of the patient's heart during pacing therapy and analyzing one or more features within the monitored electrical vectors.
Implantable medical devices (IMDs) are capable of utilizing pacing therapies, such as cardiac resynchronization therapy (CRT), to maintain hemodynamic benefits to patients. Pacing therapy may be delivered from an implantable generator, through a lead, and into the patient's heart. Basic programmable pacing parameters include pacing amplitude, pacing rate, pulse duration, and pacing pathway or vector (e.g., bipolar such as a lead tip electrode to a lead ring electrode, etc. or unipolar such as a lead tip electrode to IMD casing, or housing), which all may be configured to ensure effective therapy to the patient.
CRT may improve cardiac function and clinical outcomes through the use of permanent biventricular (BV) and left ventricular (LV) pacing. The proportion of ventricular paced beats with respect to the total number of paced and sensed beats has been associated with CRT efficacy. The proportion may be referred to as a BV or LV pacing ratio, which is the number of paced heart beats divided by the total number of heart beats. Present devices including diagnostics may track the pacing ratio.
Existing methods of morphology analysis may use template matching algorithms like WAVELET (e.g., for distinguishing supraventricular tachycardia from ventricular tachycardia). Such existing methods of morphology analysis may not be practical since such algorithms may be computationally intensive for an IMD to execute, especially on a beat-by-beat basis. Also, the electrogram (EGM) waveforms in CRT devices may be corrupted by pacing artifacts, which may make detailed template matching methods unreliable for accurate rhythm classification.